The company said there was a problem with software used to control a power converter.
“In limited cases, the hybrid system might shut down and the vehicle will stop, perhaps while being driven,” it said in a statement.
The world’s biggest automaker added that the most likely scenario is that the defect could set off a vehicle’s warning lights and “probably” cause it to enter “failsafe mode”, in which the car can still be driven but with reduced power.
“The car may stop while driving, but not suddenly,” said a Tokyo-based company spokeswoman. “It would slow down, eventually to stop.”
Toyota was aware of more than 400 cases of the problem, including 300 in Japan and 90 in North America, she said, adding that no accidents had been reported due to the defect.
Toyota and other Japanese automakers have been hit by a series of mass recalls in recent years that damaged their long-held reputation for quality and safety.